MECHANICAL  DRAWING 


STANDARDS   AND 
CONVENTIONS 


F.  R.  KEPLER 


STANDARDS  AND  CONVENTIONS 


MECHANICAL  DRAWING 


BY 

FRANK  R.  KEPLER 

Cass  Technical  High  School  Drafting  Department 


Revised  by 

DETROIT  MANUAL  TRAINING  CLUB'S 
STANDARDS  COMMITTEE 


Published  under  Authority  of 

THE  BOARD  OF  EDUCATION 
DETROIT,  MICH 


Copyright  1916, 

by 
FRANK  R.  KEPLER,  Chairman 


First  Issue  ....  October  1915 
First  Edition  .  .  .  March  1916 
Second  Edition  .  .  .  July  1916 


Printed  in 

Cass  Technical  High  School 
Detroit,  Michigan 


PREFACE  TO  FIRST  EDITION 

A  COMMITTEE  on  STANDARDS  AND  CONVENTIONS  for  Mechanical 
^~JL  Drawing  was  selected  by  the  Executive  Committee  of  the 
Detroit  Manual  Training  Club. 

Copies  of  a  preliminary  issue  of  STANDARDS  AND  CONVEN- 
TIONS for  Cass  Technical  High  were  used  as  a  basis  of  inquiry 
and  criticism.  These  copies  were  sent  out  to  fifty  representative 
concerns  in  Detroit  and  Michigan.  The  criticisms  of  a  large  major- 
ity of  the  representatives  of  these  firms  were  gathered  together, 
carefully  noted,  and  discussed.  Points  were  finally  decided  as 
the  consensus  of  opinion  seemed  to  indicate.  School  require- 
ments and  good  educational  methods  have  governed  the  decision 
of  points  which  did  not  seriously  conflict  with  good  industrial 
practice. 

This  first  edition  is  presented  with  the  hope  that  these 
STANDARDS  AND  CONVENTIONS,  determined  as  stated  above,  will 
be  generally  adopted  in  the  schools. 

The  chairman  takes  this  opportunity  to  acknowledge  the 
interest,  suggestions,  and  helpfulness  of  the  various  members  of 
the  committee. 

Signed 

F.  R.  KEPLER,  CHAIRMAN 

CASS  TECHNICAL 

L.  G.  BURGESS,  SEC'Y 

NORTHWESTERN 

P.  A.  CUMMINS 

CASS  TECHNICAL 

EDWARD  GATES 

CENTRAL 

JOHN  F.  GRANT 

EASTERN 

D.  W.  HICKOK 

WESTERN 


2O65666 


PREFACE  TO   FIRST  ISSUE 

THE  notes  and  plates  for  STANDARDS  AND  CONVENTIONS  have 
been  brought  together  by  Mr.  P.  A.  Cummins  and  myself  for 
use  in  Cass  Technical  High  School.  They  are  the  result  of  sev- 
eral years'  experience  in  teaching  Continuation,  Evening,  and 
High  School  classes,  and  are  a  study  of  the  requirements  of  mod- 
ern drafting  room  practices. 

Mr.  Carnot  Iverson,  Cass  Technical  High  School,  inked  in 
all  the  drawings  for  the  plates  and  made  the  original  drawings  for 
Plates  15  and  16. 

Friendly  criticisms  of  our  initial  copy  will  be  greatly  appre- 
ciated as  it  is  our  endeavor  to  meet  the  best  drafting-room  prac- 
tices. 

FRANK  R.  KEPLER 


PLATE  1 


Page  Ei£ht 


GENERAL  DIRECTIONS  AND  NOTES 

DIRECTIONS 
For  Laying  Out  D-size  Sheets 

Place  a  sheet  of  drawing  paper  $y2"  by  12"  upon  the 
drawing  board  so  that  the  upper  edge  is  in  line  with  the  tee- 
square.  Placing  the  tee-square  diagonally  across  the  paper 
from  corner  to  corner,  draw  portions  of  the  diagonals  near 
the  center  to  find  the  exact  center  of  the  sheet.  Now  through 
he  center  draw  a  horizontal  and  a  vertical  line  across  the 
paper.  Measure  4y2"  above  the  center  and  4y2"  below  the 
center;  through  the  points  thus  found  draw  horizontal  lines. 
These  two  lines  are  the  cutting  lines  along  which  to  trim  the 
finished  drawing,  making  the  sheet  9"  by  12".  Again  measure 
5y2"  to  the  right  and  5y2"  to  the  left;  through  these  points 
draw  vertical  lines.  Next  measure  4"  above  the  center  along 
the  vertical  line  and  4"  below  the  center  and  through  these 
points  draw  horizontal  lines.  These  four  border  lines  en- 
close a  rectangle  8"  by  11".  Observe  Plate  1.* 

A  title  block  is  used  in  all  cases.  The  title  block  will  ap- 
pear in  the  lower  right  hand  corner,  arranged  as  shown  in 
Plate  3.  The  title  block  should  be  penciled  in  complete  before 
the  drawing  itself  is  begun. 

Guide  lines  in  pencil  should  be  drawn  for  the  tops  and 
bottoms  of  all  letters  but  must  not  be  drawn  in  ink. 

Each  drawing  shall  first  be  done  in  pencil  and  submitted 
to  the  instructor  for  approval  or  corrections.  The  drawing 
is  to  be  inked  when  it  has  been  approved  by  the  instructor  and 
he  has  placed  the  word  "INK"  on  the  margin. 

When  the  drawing  is  finished,  it  shall  again  be  submitted 
for  final  approval  before  the  word  "INK"  is  cut  off.  It  shall 
then  be  trimmed  to  the  proper  size  and  handed  in. 

One  plate  from  each  set  may  be  retained  as  the  property 
of  the  school. 


*The  sheet  may  be  laid  out  without  first  finding  the  center,  hut  the 
distance  from  the  upper  to  the  lower  cutting  lines  must  be  9"  and  the 
border  rectangle  must  be  8"  by  11". 

Page  Nine 


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PLATE  2 


Ten 


DIRECTIONS 
For  Laying  Out  C-size  Sheets 

Place  the  sheet  of  drawing  paper,  provided  for  the  pur- 
pose, on  the  drawing  board  so  that  one  of  the  long  sides  is 
even  with  the  upper  edge  of  the  T-square.  Draw  a  vertical 
line  y2"  from  the  left-hand  edge  and  another  18"  to  the  right 
of  the  first.  These  two  lines  are  the  cutting  lines  along  which 
the  sheet  is  to  be  trimmed  thus  removing  the  thumb-tack 
holes  when  the  drawing  is  completed.  Leaving  1"  margin  at 
the  left  and  y2"  margin  on  the  other  three  sides,  draw  a  bor- 
der rectangle  11"  x  16y2".  Observe  Plate  2. 

Unless  otherwise  directed,  a  title  block  is  to  be  placed  in 
the  lower  right-hand  corner.  This  title  block  is  to  contain 
the  name  of  the  school,  the  title  of  the  drawing,  by  whom 
drawn,  by  whom  traced,  and  checked  as  well  as  approved,  and 
th  enumber  of  the  drawing.  It  is  to  be  spaced  and  arranged 
as  shown  in  Plate  3. 

A  Bill  of  Material  is  generally  placed  on  all  drawings  for 
shop  purposes  arid  erecting.  This  list  must  contain  the  num- 
ber of  parts,  the  material  of  which  they  are  made,  the  name 
of  the  part,  the  reference  number  on  the  drawing  and,  if  a 
pattern  is  required,  the  pattern  letter.  (The  pattern  num- 
ber consists  of  the  drawing  number  and  the  letter;  thus, 
PATT.  C-204A).  The  letters  of  the  Bill  of  Material  are  3/32" 
high,  and  the  columns  are  arranged  as  shown  in  Plate  4.  It 
may  be  placed  in  any  convenient  space  on  the  drawing  but 
preferably  above  the  title-block.  The  listing  of  the  parts  be- 
gins at  the  bottom,  a  few  spaces  being  left  at  the  top  for  the 
listing  of  additional  parts  if  occasion  demands  it.  Such  stan- 
dard parts  as  bolts,  machine  screws,  washers,  etc.,  are  listed 
but  are  NOT  DRAWN. 

The  cutting-lines,  border  rectangle,  title  block,  and  bill 
of  material  must  all  be  arranged  properly  in  pencil  before  the 
drawing  itself  is  begun.  Be  careful  to  make  the  drawing  ac- 
curate in  pencil,  making  all  corrections  before  inking  any 
part  of  the  drawing.  Do  not  begin  inking  until  the  penciled 
drawing  has  been  submitted  to  your  instructor  for  his  ap- 
proval and  he  has  placed  the  word  "Ink"  on  the  margin. 

When  the  drawing  has  been  carefully  inked  or  traced  it 
must  again  be  submitted  to  the  instructor  for  his  final  ap- 
proval before  removing  it  from  the  drawing  board.  This 
approval  secured,  the  finished  drawing  is  to  be  trimmed  to  the 
required  size,  12"  x  18",  and  handed  in. 

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STANDARDS  AND  CONVENTIONS 

P.  A.  Cummins— F.  R.  Kepler. 

The  following  conventions  and  standards  are  to  be  fol- 
lowed in  making  all  drawings: 

1.  The    sizes    of    drawings    shall    be    6"  x  9",    9"  x  12", 
12"  x  18",  18"  x  24"  and  24"  x  36 "  and  with  border  lines  as  indi- 
cated in  Plates  1  and  2.    These  sizes  are  chosen  for  the  reason 
that  commercial  stock  may  more  readily  be   cut  to  these 
dimensions  and  the  smaller  can  be  cut  from  the  larger  without 
waste.    Plate  5. 

2.  The  letters  and  figures  used  for  notes  and  dimensions 
shall  be  after  the  form  adopted — inclined  right  line  lettering. 
Plate  6. 

3.  All  notes  on  drawings  shall  be  made  with  capital  let- 
ters 3/32"  high,  made  between  light  guide-lines  that  distance 
apart. 

4.  .  Figures  must  be  made  of  the  same  height.    Fractions 
are  to  be  made  higher  than  the  whole  numbers  and  with  the 
division  line  horizontal.    Plate  6. 

5.  The   conventional  lines   of   the   kinds   and   weights 
shown  are  to  be  used  as  required  to  give  a  contrast  between 
the  object  and  other  lines.     The  beginner  often  makes  his 
object  lines  too  light.    Plate  6. 

6.  Arrow  heads  are  always  to  be  made  narrow.     They 
must  not  be  large  and  spread  out.    Plate  4. 

7.  The  Title  and  Bill  of  Material  are  to  be  laid  out  as 
shown  in  Plates  3  and  4.    The  Bill  of  Material  must  contain 
drawing  and,  if  a  pattern  is  required,  the  pattern  letter  or 
number.     It  may  be  placed  in  any  convenient  space  on  the 
drawing  but  preferably  above  the  title  block.    The  listing  of 
the  parts  begins  at  the  bottom,  a  few  spaces  being  left  at  the 
top  for  the  listing  of  additional  parts  if  occasion  demands  it. 

8.  Each  part  shall  have  a  Reference  Number,  whether 
the  part  is  detailed  on  the  drawing  or  is  a  standard  part.  Each 
number  is  to  appear  on  or  near  the  piece  if  detailed;  if  stan- 
dard it  is  to  be  placed  near  where  it  belongs,  an  arrow  show- 
ing the  exact  location.    Each  number  is  to  be  3/16"  high  and 
be  placed  within  a  heavy  circle  %"  in  diameter,  the  number 
being  of  the  same  weight.    The  number  should  be  made  first 


Page  Fifteen 


A  B  COEFGHIJKLMNOPQRSTU'V 


CONVENTIONAL    LINES 
BORDER  L/A/E 

VISIBLE   EDGE 

HIDDEN  EDGE: 


REFERENCE 


Dl  MEMS/ON          L./NE 
CENTER    L/NE 


PROJECT/ON  L/A/E 


CORRECT 


WRONG 
*< > 


PLATE  6 


Page  Sixteen 


and  then  the  circle  drawn,  so  that  the  number  will  appear  in 
the  exact  center  of  the  circle.  A  corresponding  number  shall 
appear  in  the  Bill  of  Material  with  the  name  of  the  part. 
Plate  4. 

9.  The  numbering  of  the  drawings  shall  be  on  the  fol- 
lowing basis:     The  size  of  the  sheets  shall  be  designated  as 
A  for  24"  x  36",  B  for  18"  x  24",  C  for  12"  x  18",  D  for  9"  x  12" 
and  E  for  6"  x  9".    Plate  5. 

Drawings  in  the  first  year  shall  be  numbered  from  101  to 
199;  the  second  year  201  to  299;  the  third  year  301  to  399; 
and  the  fourth  year  401  to  499.  The  first  figure  tells  at  once 
in  what  school  year  the  drawing  is  made  and  the  last  figures 
give  the  consecutive  number  of  the  drawing.  This  is  further 
divided  by  having  all  second  term  drawings  begin  with  151, 
251,  etc.  Thus  the  sixth  drawing  of  the  second  term  of  the 
first  year  made  on  a  12"  x  18"  sheet  would  be  C-156.  Drawings 
to  be  used  in  the  various  shops  of  the  school  must  be  num- 
bered consecutively  beginning  with  1101  preceded  by  the 
proper  letter  designating  the  size;  thus:  D-1102.  A  record 
of  each  drawing  shall  be  kept. 

10.  Patterns  will  be  listed  A,  B,  etc.,  in  the  bill  of  mate- 
rial.   Hence  pattern  B  on  Drawing  C-156  would  be  Patt.  C-156 
B.    Plate  4. 

CONVENTIONAL  LINES 

(See  Plate  6) 

11.  Border  lines  shall  be  heavy  full  lines,  from  1/32" 
to  1/16"  wide. 

12.  Visible  edges  and  outlines  of  objects  shall  be  repre- 
sented by  full  lines  of  medium  width. 

13.  Hidden  edges  and  outlines  of  objects  shall  be  repre- 
sented by  broken  lines,  consisting  of  short  y8"  dashes,  some- 
what lighter  than  medium  lines,  separated  by  1/16"  spaces. 

14.  Dimension  lines  shall  be  fine,  solid  lines,  interrupted 
for  the  figures  expressing  the  dimension  and  terminated  by 
long,  narrow  arrow-heads;  and  drawn  at  least  14"  from  the 
object. 

15.  Reference,  or  extension  lines  shall  be  fine,  full  lines, 
drawn  at  right  angles  to  the  edge  measured,  from  a  point  1/32" 
from  the  edge  and  projecting  1/16"  beyond  the  arrow  head. 

16.  Center  lines  shall  be  fine,  broken  lines,  consisting  of 
long  %"  dashes,  separated  by  single  1/16"  dots  and  1/16" 
spaces. 

17.  Projection  or  Construction  lines,  including  all  lines 
not  essential  outlines  or  edges  of  the  object  represented,  shall 
be  fine  1/16"  dotted  lines.    These  are  seldom  inked, 

Page  Seventeen 


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18.  A  working  drawing  is  one  made  for  use  in  a  work- 
shop, in  building  construction,  or  erecting  in  the  field. 

19.  The  representation  of  an  object  on  such  a  drawing 
must  follow  the  principles  of  orthographic  projection.    In  all 
standard  drawings  the  third  angle  is  used,    Plate  7, 

20.  The  front  view  must  be  placed  below  the  top  view, 
or  plan ;  the  end  or  side  elevation  at  the  corresponding  side  of 
the  front  view  or  elevation;  the  bottom  view  below  the  front 
elevation,    Plate  7.    If  conditions  demand,  the  end  view  may 
be  placed  at  the  right  or  left  of  the  top- view,  or  plan. 

21.  Two  views  are  generally  needed  to  represent  an  ob- 
ject.    Three  views  are  often  required  while  more  may  be 
necessary.     Sometimes  one  view  with  a  section  view  is  all 
that  is  necessary,  while  in  the  case  of  a  cylinder  one  view 
showing  the  length  with  the  diameter  stated  thus:  3"  DIA., 
will  meet  all  requirements.    Select  the  views  that  will  give  the 
best  idea  of  the  piece,  avoiding  hidden  edges.    Plate  8,  Figs.  1 
and  2. 

22.  Working  drawings  are  made  %",  1",  li/>",  2",  3",  4", 
'6",  9"  and  12"  to  the  foot,  that  being  1/16,  1/12,  i/8,  1/6,  14, 
1/3,  %,  %  and  full  size  respectively.     Details  are  made  full 
scale  or  to  as  large  a  scale  as  possible.    Scales  are  not  given 
•on  detail  drawings.    The  2"  and  4"  scales  are  to  be  avoided  as 
impractical, 

23.  Drawings  are  made  either  of  the  separate  parts  or  of 
the  various  parts  properly  assembled.    The  former  are  styled 
detail  drawings;  the  latter  assembly  drawings, 

24.  Drawings    are    made    of    objects    as    they    would 
naturally  appear  in  use  or  in  the  assembled  whole. 

25.  Show  all  details  as  near  to  full  size  as  possible  con- 
sistent with  size  of  sheet. 

ASSEMBLY  DRAWINGS 

26.  The  assembly  drawing  is  designed  to  show  the  inter- 
relation of  the  parts,  the  space  occupied  by  the  machine,  the 
name  and  number  of  each  part,  the  method  of  fastening,  cen- 
ter line  distances  which  can  be  checked  in  erecting,  etc.    The 
assembly  drawing  is  usually  made  more  elaborate  than  the 
detail  in  that  shading  may  be  done  at  times,  threads  drawn 
in  their  true  form,  or  gear  teeth  shown,  etc. 

27.  The  assembly  may  be  sectioned  in  part  to  show  the 
interior,  the  working  of  the  component  parts,  etc. 

28.  In  engine  and  machine  drawings  it  is  permissible  to 
omit  in  one  view  some  construction  which  is  sufficiently 

Page  Nineteen 


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Page  Twenty 


shown  in  another  view.    This  permits  the  showing  of  details 
in  the  mechanism  which  would  otherwise  be  obscured. 

29.  Preliminary  assemblies  are  usually  made  full  size 
from  sketches  and  are  used  by  the  designer  in  working  out 
the  action  of  the  mechanism. 

30.  Partial  assemblies  are  made  to  show  the  details  of 
any  system  connected  with  the  machine,  as  the  lay-out  of 
wiring,  piping,  etc. 

31.  Piping  and  wiring  drawings  are  often  made  in  iso- 
metric form  that  is  similar  to  a  photograph  in  which  one  pic- 
ture may  show  top,  front  and  all  details.    Such  a  drawing  aids 
the  workman  as  it  shows  at  a  glance  the  location  of  all 
couplings,  valves,  tees,  elbows,  etc. 


DIMENSIONS 

32.  The  drawings  are  dimensioned  the  actual  size  of  the 
piece  regardless  of  the  scale. 

33.  Dimensions  and  notes  must  be  at  least  14"  from  the 
drawing.-  Plate  8,  Figs.  £  and  4. 

34.  Dimensions  are  placed  so  as  to  read  either  from  the 
right-hand  side  of  the  drawing  or  from  the  bottom.    Plate  8 
and  Plate  10. 

35.  All  notes  are  placed  either  horizontally  or  vertically, 
never  at  an  angle.    Plate  8,  Fig.  4. 

36.  Everything  must  read  from  the  lower  and  right- 
hand  side  of  the  sheet.    Plates  8,  9  and  10. 

37.  Dimension  figures,  including  fractions,  are  placed 
at  the  center  of  the  dimension  line,  unless  the  space  is  very 
limited,  in  which  case  the  arrow-heads  and  figures  are  placed 
on  the  outside  of  the  space  dimensioned.    Plate  10. 

38.  The  common   fractions  in   y2's,   14 's,   %'s,   1/16's, 
1/32's,  1/64's  only  are  used.     Where  very  accurate  work  is 
demanded,  decimals  are  used. 

39.  The  division-line  of  fractions  must  be  in  line  with 
the  dimension  line,  and  never  inclined.    Plate  10. 

40.  On  drawings  of  machinery  inches  ale  used  up  to  48". 
48  inches  and  above  are  expressed  in  feet  and  inches,  thus: 

4 EL  10^.     Plate  10.    Where  all  dimensions  are  in  inches  the 
inch  marks  may  be  omitted.    Plate  2 

41.  Inches  alone  are  used  in  drawings  of  furniture  and 
much  cabinet  work  and  interior  finish.    This  is  also  the  gen- 
eral practice  in  the  automobile  industry. 

42.  Over  all  dimensions  should  be  placed  well  outside 
the   drawing;    shorter   dimensions   are   placed   inside   these. 

Page  Twenty-one 


.    3 


PLATE  9 


Page  Twenty-two 


Plates  8  and  9.    A  series  of  dimensions  should  be  so  arranged 
as  to  facilitate  checking.   . 

43.  Dimensions  must  not  be  too  far  removed  from  the 
part  dimensioned.    Measurements  are  placed  so  as  to  aid  the 
checker  and  the  workman.    Dimensions  are  often  well  placed 
between  the  views. 

44.  Keep  dimensions  off  the  figure  except  where  there 
is  a  possibility  of  confusing  the  workman.    Plate  8,  Fig.  2. 

45.  Keep  related  dimensions,  i.  e.,  a  length  and  width,  on 
thp  same  view  if  possible. 

46.  Dimensions  given  in  one  view  must  not  be  repeated 
in  another. 

47.  Avoid  dimensioning  from  hidden  edges. 

48.  Never  use  center  lines  for  dimensions. 

49.  Base  dimensions  from  center  lines  and  finished  sur- 
faces.   Make  the  drawing  fool  proof  by  tying  up  all  holes  or 
cuts  to  center  lines  or  finished  surfaces.    Plate  8,  Fig.  4;  Plate 
9,  Fig.  1. 

50.  Place  center  lines  through  the  centers  of  all  circles 
and  symmetrical  drawings.    Show  center  lines  for  every  hole. 
Plate  9. 

51.  Dimension  to  center  lines  of  circles,  not  to  circum- 
ferences.   Plate  9,  Fig.  1. 

52.  Circles  are  dimensioned  by  their  diameters;  arcs  by 
their  radii.     All  Radii  should  be  marked  R  or  Rad  and  all 
diameters  Dia  or  D,  Ream,  Turn,  Bore,  Core,  etc.    Plate  9,  Fig. 
1,  and  Plate  10. 

53.  Where  there  are  several  diameters  in  a  given  length 
it  is  better  to  give  them  across  the  length  rather  than  in  an 
end  view.    Plate  9,  Figs.  2  and  3. 

54.  Never  cross  a  dimension  with  a 'line.    Break  section 
lines  for  a  dimension  or  note  if  placed  in  a  sectional  area. 
Plate  11,  Fig.  1. 

55.  Since  shop  drawings  are  not  to  be  scaled  give  all 
necessary  dimensions  for  laying  out  and  finishing  the  work. 

56.  Drawings   are   figured   for  the   machinist,    cabinet 
maker,  or  builder,  as  the  case  may  be.     Be  careful  to  give 
such  dimensions  as  will  be  needed  by  the  mechanic  in  laying 
out  the  work.    All  figuring  is  up  to  you.    Add  all  partial  dimen- 
sions and  give  "over  all."    Leave  no  adding  or  subtracting  for 
the  workmen.    This  is  your  job.    He  has  enough  to  figure  out 
without  doing  yours. 


Page  Twenty-three 


D/MELNS/ONS 


3-7- 


a-7 


RAD 


REVERSE  r /CURES    AT  6O* 


PLATE  1O 


Page  Twenty-four 


NOTES 

57.  Do  not  be  afraid  to  use  explanatory  notes.     Clear- 
ness is  all  important. 

58.  All  left-hand  threads  should  be  plainly  marked. 

59.  Handed  pieces  should  be  marked  Right  (or  Left)  as 
shown. 

60.  On  tool  details  it  is  customary  to  add  a  note  below 
regarding  Material,  as  Tool  Steel,  etc.,  etc.    Harden  and  Grind, 
etc. 

61.  On  tool  details  the  dimensions  of  the  raw  stock  from 
which  part  is  to  be  made  are  sometimes  given. 

62.  Use  abbreviations  where  possible  but  be  sure  the 
abbreviation   is   commonly   used.     The   workman   reads   the 
drawing  not  your  mind. 

SECTION  VIEWS 

63.  A  section  view  shows  the  surface  as  made  by  the 
passing  of  a  plane  through  a  piece.    The  purpose  of  a  section 
is  to  show  the  shape  of  cores,  thickness  of  stock,  interior 
mechanism,  and  assembly.    Plate  11. 

64.  The  point  at  which  a  section  is  made  is  indicated  by 
a  short  and  long  dash  line,  similar  to  a  center  line,  and  let- 
tered: as  A-A.     Plate  11,  Fig.  1. 

65.  The  surface  cut  by  the  plane  of  section  is  indicated 
by  lines  at  45  degrees  spaced  in  proportion  to  the  size  of  the 
drawing,  usually  about  1/16"  apart.    Section  all  details  as  for 
cast-iron.     The  various  styles  of  cross-hatching  need  not  be 
used  to  indicate  the  material,  often  that  for  cast-iron  and 
babbitt  only  being  used  in  actual  practice.     The  material  is 
otherwise  stated  in  connection  with  the  name  of  the  piece. 
Cross  hatch  lines  for  cast-iron  and  for  babbitt  are  fine.    Plate 
11. 

66.  Never  section  bolts,  nuts,  screws,  shafts,  spindles, 
keys,  arms  of  wheels  (lengthwise),  gear-teeth,  etc.    Plate  11, 
Fig.  2,  Plate  12,  Fig.  1. 

67.  Never  show  hidden  edges  behind  the  line  of  section, 
unless  clearness  positively  demands  it. 

68.  Make  half  section  rather  than  full  section  views. 
Plate  11. 

69.  Adjoining  section  areas  have  section  lines  running 
in  opposite  directions.    Plate  11. 


Page  Twenty-five 


SECT /OH     O/V    A- A 


PIG. 


PLATE  11 


Twenty-six 


8P-+3T 

F/G.  /        CAST  SPUR  GEAR 


Q  f».  40  T   OEPTH  O/-  CUT  O. 

.2.      CUT   SPUR  GEAR 


Page  Twenty-seven 


6  CFtE  W     THREADS 


/a  U.S.STD.        iz  u.s.  $TD.  THD.  PER  IN  L.H< 

THP.  PER   IN.  FIG.   / 


TAPPED    HOLES 


BfitGG* 
PIPE     THD. 


FIG.  3 


DEEP 


\\ 

i1            'i 
1            i 

|! 

!!     ! 

! 

\\ 

*U 

!i 

!!     ! 

i 

i 

II 

II 

ii 

ii     i 

i 

FIG. 


PLATE     13 


Page  Twenty-eight 


THREAD^ 

70.  U.  S.  Standard  and  V-threads  should  be  indicated 
by  alternate  light  and  heavy  lines.     The  diameter  and  pitch 
should  always  be  given.    Plate  13.    Either  method  as  shown 
in  Fig.  1  may  be  used. 

71.  Any  other  than  the  standard  thread  should  be  stated 
in  a  note.    If  a  screw  has  a  left-hand  or  multiple  thread,  a  note 
should  call  attention  to  the  fact.    Plate  13,  Fig.  3. 

72.  A  tapped  hole  should  be  shown  by  a  circle  indicating 
the  size  of  the  drill  and  a  larger  concentric  circle  in  hidden 
edge  line,  indicating  the  size  of  the  tap.    A  note  should  state 
the  diameter  and  number  of  the  tap,  thus:  l"-8  TAP.  U.  S.  Std. 
Plate  13. 

73.  Never   make   detail   drawings   of   standard   screws, 
bolts  and  nuts. 


FINISH 

74.  The  finish  mark,  "//'  made  crossing  the  line  indicat- 
ing the  surface  finished,  shows  that  the  surface  is  to  be  fin- 
ished as  left  smooth  by  the  tools.     Plate  8,  Fig.  4;  Plate  9, 
Fig.  1.    A  small  fraction  placed  a  little  above  and  to  the  right 
of  the  finish  mark  indicates  the  amount  required  for  finishing. 
Plate  11,  Fig.  1. 

75.  Other   special   finishes   as  turn,   bore,   drill,   knurl, 
ream,  spot-face,  as  well  as  core,  are  so  stated  on  the  drawing. 
Plate  9  and  Plate  13. 

76.  If  a  piece  is  to  be  finished  all  over,  the  note,  "Finish 
all  over"  (F.  A.  O.),  may  be  placed  near  the  drawing  of  the 
piece  or  in  connection  with  its  name  in  the  bill  of  material. 
Plate  9,  Fig.  2. 

77.  On  all  machine  parts  use  following  note:    "Remove 
all  burs,"  "Break  all  sharp  machined  edges." 


Page  Twenty-nine 


PLATE  14 


Page  Thirty 


MACHINE.  SCREW   HEADS. 


HEXAGON 


pl 


ACROSS      FLAT*B 


t 
D>+ 


FILLISTER. 


BUT  TOW 


SQUARE 


T*D 

ACROSS      PLAT  -  B 


WHEN  O 
ROUND 


£•-.£ 


CO  UN  TERSUNK 


PLATE  15 


Page  Thirty-one 


w 


£ 


3E  T     -3  CHEWS. 

F^ 


cp 


i 


-*-^7 


'<\ 


Qi<v| 


-£)  + 


4    f  ~ 


ROUND 


CUP 


CONE 
'SET    SCREW   ENDS 


FLAT          fLAT  P/VOT    RO UND  Pi VOT  HANGER 

FUVELTS 


ROUNO   HEAO 


STEEPLE  HEAD 


n 


C~D/AM     OF   BUTTON 
HEAD 


COUNTERSUNK          CONJCAL    HEAD 


ZJ 


BRIGGS    STANDARD    P/PE     THREADS 

PERFECT 


TA  PE.  R  Or  P/PE  END  *%  PER  FT.  ;  Of?  £  PER  /A/. 


PLATE   16 


Page  Thirty-two 


LIMITS 

78.  In  cases  where  great  accuracy  is  needed  the  work- 
man is  required  to  turn  out  the  piece  correct  within  limits. 
These  vary  a  hundredth  to  a  ten-thousandth  for  instance, 
according  to  the  accuracy  required. 

79.  Limits  are  expressed  decimally.     The  amount  over 
size  is  placed  above  the  dimension  line  after  the  dimension 
figure  while  the  amount  under  size  is  placed  below  the  dimen- 
sion line. 

PATTERN  AND  FORGING  DRAWINGS 

80.  There  is  a  growing  tendency  on  the  part  of  manu- 
facturers to  send  full  size  pattern   drawings   showing   core 
prints,  draft,  allowance  for  finish,  parting  lines,  etc.,  into  the 
die  sinking  or  pattern  rooms.     These  drawings  are  usually 
inked  in  on  the  original  pencil  work  to  avoid  the  distortion 
produced  by  the  tracing  cloth  and  blue  printing.    Pattern  and 
die  drawings  are  usually  made  by  experienced  pattern  or  die 
makers  who  have  been  trained  in  drafting.     Such  drawings 
are  intended  to  supplement  the  ordinary  drafts  made  by  each 
pattern  maker  or  the  foreman. 

81.  Pattern  drawings  should  contain  certain  notes  to 
assist  the  pattern  maker  such  as  "Break  all  sharp  edges  ex- 
cept as  noted,"  etc. 

82.  Forging  drawings  should  be  very  explicit  in  regard 
to  the  shape  of  the  part.    All  centers  should  be  located  and 
drafts  shown.     Dimensions  not  related  to  or  required  by  the 
pattern  or  die  maker's  work  need  not  be  shown. 

CHECKING  DRAWINGS 

1.  See  that  projections  and  sections  are  correct. 

2.  On  assembly  drawings  check  for  interference   and 
clearances. 

3.  See  that   general   conventions   and   standards   have 
been  observed. 

4.  Check  all  dimensions  in  regard  to  arrangement  and 
accuracy. 

5.  See  that  all  finished  surfaces  are  marked. 

6.  See  that  the  bill  of  material  is  complete  and  correct. 

7.  See  that  the  title  and  drawing  number  are  correct. 

8.  Check  all  notes  for  arrangement. 

9.  See  that  proper  weights  of  lines  and  size  of  letters 
and  figures  have  been  used  and  that  the  drawing  is  correct  in 
every  detail. 

Page  Thirty-three 


L/MITS 


s 

s^ 

1 

£ 

1 

s 

k 

«0 
5 

^  S 

3i  ^ 

*v 

X 

X, 

^  ^ 
s  N 

-»- 

,  .fo/ 

t 


/. 


CENTERS 

—  (*>|jo^ 


GR/MD/MG 


"B  "CF/V  TER 


B  C£/VTER 
6 HOLES 


F.A.  O. 


PLATE  17 


Thirty -four 


VJ»X|M   '°)]<b 


nn 


*    * 

O         5! 

a    5 


Mf 


,^1 


5   1 


— f/- 
-r^<? 


, 1-¥- ,-r    n^ 


V/- 


«*) 


L_ 


PLATE  18 


Page  Thirty-five 


DECIMAL  EQUIVALENTS  OF  FRACTIONAL 
PARTS  OF  ONE  INCH 


& 

_3_' 
64 


,015625 
03/25 
046875 
0625 


64 


32 


64 

_9_ 
64 


09375 
109375 


, 
8 


64 
13__ 
64  7 


15625 
17)875 


3_ 

Iff 


203125 


64 
17 


234375 
25 


64 
2/ 


.£ 

/6 


64^ 
23  32_ 
64 

25 

64^3 
27  £1 
64 

23 j 

64,5 


B 


.359375 

.375 

.390625 


.4375 


64 


..484375 


JL.5 
2 


33 

64 
37 


6*4 

4J. 

642/ 
43^2- 


5 
3" 


.515625 

.53125 

.546875 

.5625 

.578125 

.59375 

.609375 

.625 

.640625 


64 


45 (S 


.703125 


32 


64 
45 


.734375 
.765625 


5' 
6? 

M_ 
64^7 

5532 


.796875 


13 


.84375 


64 
57 


64 

6L 

64^ 

6332 
64 


/5 


,875 
.890625 
.9O625 
.921875 
.9375 


/6 


.96875 
.984375 


PLATE  19 


Thirty-six 


U.S.  STANDARD 
THREADS  BOLTS  AND  NUTS 


ETER 


O.OFTH'DS 
PER  INCH 


OT 
EAD 


DIAMETER 
AT  RO 
OF  THR 


DIAMETER 
OF  TAP  DRILL 


DIMENSIONS     OF     NUTS 
AND    BOLT    MEADS 


ACROSS 
FLATS 


IB 


<o 


o  o  u_ 

<  O  0 


THICKNESS 
F  NUT 


!-< 
r  S 

on 

LJ  u. 
310 


20 


0.185 


'/e 


0.578 


0.707 


Vie 


8 


0.240 


1/4 


0.686 


0.840 


3/8 


16 


0.294 


Vie 


'!/.€, 


0.794 


O.972 


Vs 


14 


0.345 


25 


5/32 


0.902 


05 


13 


O400 


V8 


I.OII 


1.237 


~w 


vz 


12. 


0.454 


1.119 


1.370 


It 


0.507 


iw 


I.Z27 
1.444 


I.5O2 


Vs 


3/4 


10 


0.6ZO 


1.768 


76 


0.731 


.660 


2.033 


8 


O.838 


1.877 


71.29S 


O.939 


2.093 


2563 


1.064 


Z.310 


2.S28 


1.158 


2.527 


3.O93 


IA 


1.283 


2.743 


3.358 


I'/Z 


51/21 


1.389 


Z.960 


3.623 


1.490 


3.176 


3.88e 


1.615 


3.393 


4.1S4 


)7/8 


4  'A 


1.711 


3.G09 


4.419 


1.961 


3  'A 


4.043 


2.175 


3% 


A476 


5.479 


2'/z 


2.4Z5 


414 


A909 


6.OIO 


Z.629 


^.342 


6.540 


2.879 


5.715 


7070 


3'/4 


314 


3.IOO 


5% 


6.Z08 


7600 


3.317 


6.641 


8.131 


27s 


3.567 


7074 


8.661 


4J4 


2% 


3.798 


7.SO& 


4  ' 


4.028 


7.941 


4% 


4.255 


5.374 


4V4 


3% 


2'/z 


4.480 


8-807 


IO.782- 


5J/4 


4.730 


9.240 


IK3I2 


4.953 


8% 


9.G73 


M.84Z 


i'/z. 


4% 


5-*/4 


5.203 


IO.IO6 


IZL.373 


5.423 


\  0.539 


12.^03 


PLATE    20 


Thirty-seven 


TRACING 

It  is  often  desirable  to  make  a  more  permanent  and  service- 
able record  of  a  drawing  than  would  be  possible  if  only  the  inked 
original  drawing  were  used.  To  accomplish  this  a  tracing  of  the 
penciled  drawing  is  made  on  tracing  cloth.  From  this  tracing  as 
many  blue-prints  as  desirable  may  be  made — these  are  durable, 
since  they  will  withstand  the  wear  and  the  danger  of  erasure  from 
the  weather  and  hard  usage. 

The  tracing  cloth  should  be  cut  somewhat  larger  than  the 
drawing,  so  that  the  thumb-tack  holes  may  be  removed  when  the 
tracing  is  trimmed  to  the  proper  size.  This  can  readily  be  done, 
since  36"  cloth  actually  measures  37"  wide,  being  36"  wide  between 
the  red  lines  near  the  edge. 

Tack  the  cloth  down  to  the  board  so  that  it  will  be  tight  and 
i'ree  from  wrinkles,  as  the  tracing  may  be  done  more  rapidly.  The 
cloth  should  have  no  creases  or  breaks  in  it  from  ill  usage.  Either 
the  dull  or  the  glossy  side  of  the  cloth  may  be  used.  A  great  many 
prefer  and  use  the  dull  side  because  in  the  drafting  room  correc- 
tions in  pencil  may  more  readily  be  made  on  this  side  than  on 
the  glossy  side. 

Dust  the  surface  over  with  chalk,  magnesia  or  talcum  powder. 
Rub  this  lightly  into  the  surface  and  brush  all  the  loose  particles 
off  thoroughly  to  rid  the  surface  of  grease  and  grit  and  to  insure 
a  ready  flow  of  the  ink. 

In  order  to  maintain  a  uniform  width  of  line  throughout  keep 
the  same  amount  of  ink  in  the  pen,  about  a  quarter  of  an  inch  at 
the  most.  Keep  the  pen  clean.  It  will  be  necessary  to  clean  the 
pen  often,  as  little  particles  of  chalk  will  be  picked  up  which  inter- 
fere with  the  even  flow  of  the  ink.  If  it  is  impossible  to  complete 
the  whole  tracing  at  one  sitting  finish  one  part,  including  circles, 
straight  lines,  medium  and  fine.  This  is  most  desirable,  as  the 
cloth  is  liable  to  stretch  during  the  intervening  time  between  sit- 
tings, making  it  difficult  to  readjust  the  tracing  to  the  drawing. 

Erasing — Use  an  ordinary  eraser  in  erasing.  Never  use  one 
with  sand  in  it.  Never  use  a  steel  eraser.  These  either  destroy  the 
surface  of  the  cloth,  making  it  impossible  to  retrace,  or  a  hole  is 
cut  in  the  cloth,  ruining  the  whole  tracing.  After  erasing  it  is  often 
necessary  to  build  up  from  a  fine  line  to  one  of  full  weight. 


Page  Thirty -eight 


University  of  California 

SOUTHERN  REGIONAL  LIBRARY  FACILITY 

Return  this  material  to  the  library 

from  which  it  was  borrowed. 


SEP  241940 
SEP  2  4 1990 


